1. Field of the Invention
The present invention is related to a grinder robot which grinds a workpiece using a grinder equipped at the tip of the robot arm and by moving the grinder towards the workpiece. Especially, this invention is related to a grinder robot by which a workpiece can be grinded quickly and accurately.
2. Description of the Prior Art
In general, a grinding machine controls a grinder to move relatively to and from a work by a position feedback loop. In other words, a grinding machine in prior arts controls grinding points of a grinder to be target positions for grindings by a position loop, and makes a finishing surface to be a target surface.
However, the grinding machine, in which a grinder is controlled to move by a position loop as mentioned above, detects only positions by the loop. It may, therefore, damage a grindstone by forcing it to grind a rugged surface of a workpiece if the grinder is set to grind directly towards a target position. This is because the grinder cuts into the rugged surface. To avoid this, the grinder can be moved slowly in every shuttle move so as to reach the target position gradually. In this case, however, a problem of increasing processing time arises.
In order to avoid disadvantages arising from the use of this kind of grinder robot controlled by a position loop the force given to the grinder can be detected and the robot arm's movement can be controlled so as to keep the force constant. In this method, however, it is difficult to grind a work surface completely smooth, because it cannot control the position of grinding point.